![](http://newport.pmel.noaa.gov/nemo_cruise98/icons/ventplume-icon.jpg) |
Many scientists think that life on Earth
started in one of two places -- on the sea surface exposed to lightning
and sunlight, or at the bottom of the ocean in hydrothermal vents.
In the late 1970's, scientists on a routine study
of the ocean floor in the Pacific made a discovery. On the East Pacific
Rise not far from the Galapagos Islands, nearly 8000 feet below the
surface, was a strange alien landscape littered with what looked like
chimneys expelling clouds of black smoke. Surrounding these chimneys was a
unique type of ecosystem that had never been seen before. Until this day,
science had always assumed that all life on Earth obtained its energy from
the sun. The plants convert sunlight into energy through a process called
photosynthesis. The plants, in turn, provide food for countless species of
animals in a complex web of life. But here was proof for the first time
that life could be sustained by the earth itself.
Science
had discovered deep-sea hydrothermal vents. These vents occur in
geologically active regions of the ocean floor. Within these regions,
seawater seeps down deep into the earth's crust through cracks and
fissures in the ocean floor. The intense heat of magma below the surface
then heats this water. As the water is heated to a boil, it expands and
rises back to the surface. On it’s way back up through the cracks
through which it fell, the hot water dissolves minerals and other
chemicals from the rock. When it reaches the ocean floor, the water is a
dark, chemical soup. Some of the minerals precipitate out of the seawater
and harden on the rim of the vent. Over time, the rim of the vent is built
up into a tall, chimney-like structure. The dark color of the water
spewing forth from these vents has earned them the name, "black
smokers". The temperature of the water coming out of these vents
exceeds 360º. The real surprise was the discovery that a myriad of life
forms actually live and thrive around these vents, totally cut off from
the world of sunlight.
|
![](back_md_wht.gif)
|